A Keck School of Medicine of USC research study using cell phones to survey youngsters about sedentary behavior has given scientists what they believe is an accurate snapshot of real-time sedentary activity among children than an after-the-fact survey could accomplish.

Yue Liao, lead author and a doctoral student in the Department of Preventive Medicine and the Institute for Health Promotion and Disease Prevention Research at the Keck School, said, “Using this method, we could capture daily behavior and ask questions about who the kids were with.”

The research was recently published online in the Journal of Physical Activity & Health. Genevieve Dunton, assistant professor of preventive medicine at the Institute for Health Promotion, was principal investigator.

The purpose of the research was to determine the most promising intervention targets for increasing physical activity among youngsters from the ages of 9 to 13. The goal was to learn where the children were, whom they were with and what they were doing when they weren’t at school, thereby revealing sedentary behavior patterns.

Working with a team led by Stephen Intille from Northeastern University that develops mobile phone health technology, the USC investigators sent 120 children 20 electronic surveys over a four-day period that included two weekdays and two weekend days. The surveys were sent randomly over phones supplied by the team; the phones’ only feature was to prompt the youngsters and accept answers to the survey, Liao said. Sedentary behavior was divided into productive (homework, reading) or leisure-oriented activity (playing video games, watching TV).

Seventy-seven percent of all the prompted surveys were answered by the children. The surveys demonstrated that the youngsters were usually at home with family members when they were least active. Fifty-eight percent of the reported sedentary activities occurred with family members, while 26 percent occurred while the children were alone.

“This could indicate an opportunity for family intervention,” Liao said.

The team also found that the children were six times as likely to engage in leisure-oriented sedentary behavior instead of productive sedentary behavior when with friends, and when alone, were equally likely to engage in leisure or productive sedentary behavior.

Boys participating in the survey were three times as likely to engage in leisure-oriented sedentary activities over productive sedentary activities when not at school, Liao said. Girls were equally likely to engage in leisure-oriented and productive sedentary activities.

by Leslie Ridgeway